1. Field of the Invention
The present invention relates to a color correction definition producing method of producing a color correction definition defining the association between coordinate values on a color space corresponding to colors before and after the color correction, a color correction definition producing apparatus, and a color correction definition producing program storage medium, which is incorporated into a computer system, storing therein a color correction definition producing program causing the computer system to operate as the color correction definition producing apparatus.
2. Description of the Related Art
In a technical field of printing, a photograph and the like, in the event that an image on a reversal film is transferred onto a printing paper or a photographic paper to make a printed matter or a photograph, it often happens that an operator applies a color correction to form a high quality of image having the tone of a color, which is visually preferable for a person, on the printed matter or the photograph.
Hitherto, for forming such a high quality of image, there is use a specified system for producing a printed matter or a photograph to optimize the system in accordance with experience of an operator of the system.
For example, in case of the printing, when an image on a reversal film is read by a scanner, image data from the scanner is corrected. An image is printed on a printing paper with printing ink in accordance with the corrected image data, so that a preferable tone of color image is produced. At that time, a correction parameter for correcting the image data derived through the scanner is optimized in accordance with know-how based on the experience of an operator of the scanner, taking into consideration properties of the system in its entirety including printing papers, printing ink and the like. That is, a know-how of image formation, in which an image having a preferable tone of color is formed from an image on a reversal film, is possessed by the operator of the scanner. Here, it is assumed that the operator of the scanner optimizes the correction parameter for a combination of a certain film and printing ink so that an image having a preferable tone of color is obtained. However, in the event that the film and/or the printing ink are replaced by other film and/or printing ink, the correction parameter will be changed to an inappropriate correction parameter. Thus, in this case, there is a need to optimize the correction parameter again.
On the other hand, in case of the photograph, a reversal film is loaded on a laboratory system and adjusted light for exposure is projected onto the loaded reversal film, so that a corrected image is obtained. The corrected image thus obtained is printed on a printing paper to form an image having a preferable tone of color. At that time, a balance among R light, G light and B light for the exposure and an exposure time are optimized by an operator of the laboratory system and an automatic control mechanism of the laboratory system, taking into consideration properties of the system in its entirety including films, a light source, printing papers and the like. Further, also with respect to a combination of a sort of a film and a sort of a printing paper, there is selected such an optimum combination that a preferable tone of color image can be obtained. That is, a know-how of image formation, in which an image having a preferable tone of color is formed, is possessed by the operator of the laboratory system, a maker of the laboratory system and a maker of the film. Here, it is assumed that an exposure time or the like is optimized for a combination of a certain film and a certain printing paper so that an image having a preferable tone of color is obtained. However, for example, in the event that the film is replaced by another film developed newly, the combination of the film and the printing paper and the exposure time will be inappropriate for the new film. Thus, also in this case, there is a need to optimize the exposure time and the like again.
Thus, in both the cases of the printing and the photograph, there is a need to do over again an optimization to form an image having a preferable tone of color, whenever a film and the like is replaced by a new type of one according to a development of products.
Further, recently, as digital technology advances, it is increased that a transfer of images is performed among different industries and media. For example, in the event that instead of distribution of printed papers, images of the printed matter appears in a home page of an internet, the image of the printed matter will be converted into an image of a television, which is not so related to the printing industry hitherto. Further, for example, it begins that one shot of an image photographed by a home video is printed out by a printer of a personal computer, or outputted on a printing paper for a photograph. In the event that such a transfer of images is performed, it is desired that a high quality of image having a preferable tone of color as mentioned above is obtained at the received end of the image. However, according to the prior art, the above-mentioned know-how is merely allowed to be used only in the individual industries such as the printing industry and the photographic industry, but is not allowed to be used in a different industry on a common basis.
In order to solve the above-mentioned problems, there is considered a method in which colors of images before and after the color correction and image data are derived by an operator and the like, so that a know-how possessed by the operator and the like is extracted in form of a color correction definition such as a Look Up Table (LUT) which defines the association between a color of an original image and a color of an image after the color correction.
However, in the event that an operator performs a data operation, the operator performs an operation based on the original image. For example, in the event that the original image is concerned with a portrait image, the operator performs such an operation that an image wherein skin color is clear can be obtained, and in the event that the original image is concerned with a landscape image, the operator performs such an operation that an image wherein colors of leaves and color of the sky are clear can be obtained. Thus, according to the color correction definition extracted in accordance with the way as mentioned above, it is possible to reproduce an adequate color correction for colors included in the original image. However, it is not always expected that it is possible to reproduce an adequate color correction for colors other than the colors included in the original image. In other words, in order to apply an appropriate color correction to the respective one of the various types of images, there is a need to use in different ways the color correction definition depending on the respective one of the various types of images.